The present invention relates to an asynchronous transfer mode (ATM) control apparatus and, more particularly, to an ATM control apparatus utilizing asynchronous transfer mode technique which is a high-speed information transfer/exchange technique used with a wide area ISDN.
There are some known conventional techniques to connect a plurality of local area networks (LANs), such as the Ethernet, by using bridges and routers so as to expand the number of communication terminals connected to the LANs and to reserve pass-bandwidths for communication. Further, a technique to use a hub having a switching function, namely a switching hub, to connect a plurality of communication terminals has been developed recently so as to expand the number of connected communication terminals and to reserve pass-bandwidth for communication between LANs. The aforesaid conventional techniques are embodied by a configuration which uses a concentrator having a switching function, and which is constituted to select a LAN port of a bridge, a router, a switching hub, or the like, from which data is outputted, in accordance with a media access control address (referred as "MAC address", hereinafter) in a LAN, such as the Ethernet.
Meanwhile, an asynchronous transfer mode (ATM) exchange system has been developed and standardization of the ATM has been discussed so as to simplify a protocol, aiming at a goal of high quality data transmission. In the ATM exchange system, information is divided into fixed-sized (53 bytes) blocks and each of the divided information is made into an ATM packet, then the ATM packets are sequentially sent out. Thereby, it is possible to reduce delay during information exchange, while keeping high transmission efficiency as in conventional packet exchange.
Further, an ATM-LAN, using the ATM transmission technology, has been developed as a LAN capable of dealing with multimedia. By using the ATM-LAN, image, sound, text, and the like, can be transmitted at high-speed while the functions of a conventional LAN is maintained.
As a first configuration for applying a switching hub on a conventional LAN to the ATM-LAN, a unit which serves as a bridge for connecting LANs, a LAN terminal, and a unit for assembling and dissembling an ATM packet, is provided at each LAN port of the switching hub, and the unit negotiates data transmission traffic handling with the switching hub (ATM switch).
However, according to the aforesaid first configuration, each unit provided in the LAN port need a function to assemble and disassemble ATM packets as well as a network administrating function by using an OAM (Operation, Administration and Maintenance) cell. Since each unit negotiates data transmission traffic with the ATM switch, there is a problem in that the amount of information which the ATM switch has to deal with increases.
Further, as a second configuration for applying a switching hub for a conventional LAN to the ATM-LAN, a switching hub for LAN is used to connect LANs, and when data is to be sent outside of the LANs which are connected to the switching hub, it is outputted to an ATM network through an ATM interface via an ATM switch.
However, in the second configuration, pass-bandwidth can not be used effectively when LANs, connected to the switching hub for LAN, are switched, which limits speed of transmitting information. Furthermore, two switching units, a switching unit for LAN and a switching unit for ATM, must exist. The two switching units in a single configuration may be regarded as being redundant when efficiency of configuration of the system is considered. In addition, there is a problem in that the amount of information which the ATM switch has to deal with increases, as in the aforesaid first configuration.
Further, since the ATM network technique is mainly developed as a large and global scale network technique of the next generation, most examples of the developed ATM network systems are naturally for relatively large scale networks, especially when an ATM exchange apparatus is developed. As for examples, the ATM-LAN is developed in limited topologies, such as a star, a ring, and so on.
However, the goal of the aforesaid ATM-LAN systems is to effectively configure LANs in an ATM network, and there is a problem in that the cost of manufacturing an interface increases in order to use conventional software for a network and to connect the ATM network to conventional hardware. In other words, there are many discussions about topologies of ATM-LAN in which the ATM network tends to be considered as prime importance in the discussion. Therefore, when a conventional LAN (e.g., Ethernet and token ring) is used in an ATM-LAN, since optimization of the configuration of the ATM network is mainly considered as a matter of importance, there is a possibility that the load on conventional software and hardware for a LAN system increases.